octane rating and engine performance
In Texas, the minimum octane rating is 87. On a recent trip to Glacier, I noticed a lot of the fuel in states like CO, WY and MT, the octane was 85, and you had to buy the mid-grade to get 87 and abov...
Forum Discussion
Atlee wrote:
The owners manual for my 2014 F150 w/ 3.5L Ecoboost states unequivocally to never use 85 octane gasoline, even when driving in mountain states.
It does recommend using premium gasoline when hauling or towing. I've never followed this recommendation. Always used regular gas when towing my trailer. However, after using regular gas this last large trip we went on (8800 miles), from Virginia to Florida and over to Santa Rosa, NM, I did put premium in the truck knowing I would be pulling in high altitudes from that point on.
I keep a gas log, and hand figured my mileage on each tank. The first leg using regular gas went like this. $871.01 // 335.242 gallons // 8.2290 MPG.
From eastern New Mexico until I got back home the numbers went like this. $1,855.02 // 552.281 gal // 11.1909 mpg.
There was definitely a very noticeable increase in miles per gallon, however strictly $ wise, it's still cheaper to use regular.
That said, I believe now when I'm towing in the east, I will use premium gasoline. I figure the engine will like it better.
I think there's a few things you're conceptually mistaken on. First, the effects of altitude are largely negated with forced induction. Second, the requirement for a particular octane generally goes down as the air gets thinner.
3rd, you'll generally see better performance and maybe slightly better mileage at any altitude with premium in an Eco boost, as it's designed to run on it. Last, most of your mileage difference from E to W vs W to E is attributable to partly altitude gain/loss, but mostly due to prevailing winds making Westward travel generally into the wind and Eastbound with the wind.
